1. Field of the Technology
The present technology relates to a toner and a method for manufacturing the same.
2. Description of the Related Art
Toners for visualizing latent images are used in various image forming processes and for example, are used in an electrophotographic image forming process.
In general, in image forming apparatuses employing the electrophotographic image forming process, a desired image is formed on a recording medium by executing a charging step, an exposure step, a developing step, a transfer step, a fixing step and a cleaning step.
At the charging step, a photosensitive layer on the surface of a photoreceptor drum serving as a latent image bearing member is charged uniformly. At the exposure step, signal light of an original image is projected on the surface of the photoreceptor drum that is being charged to form an electrostatic latent image. At the developing step, a toner is agitated to be charged, and the charged toner is supplied onto the surface of the photoreceptor drum so as to visualize the electrostatic latent image. At the transfer step, a toner image on the surface of the photoreceptor drum is transferred to a recording medium such as paper and OHP sheets. At the fixing step, the toner image is fixed onto the recording medium under heat, pressure and the like. At the cleaning step, the toner and the like remaining on the surface of the photoreceptor drum after the toner image is transferred are eliminated and cleaned with a cleaning blade. Transfer of the toner image to a recording medium may be performed through an intermediate transfer medium.
The electrophotographic toner for use in such image formation is manufactured, for example, by a knead-pulverization method, a polymerization method represented by a suspension polymerization method, an emulsification polymerization method and the like. Among them, in the knead-pulverization method, the toner is manufactured in such a manner that toner materials including a binder resin and a colorant as main components, to which a release agent, a charge control agent and the like are added as necessary and mixed, are melt-kneaded, cooled and solidified, then subjected to pulverization and classification.
In recent years, numerous efforts have been made in various technical fields from a viewpoint of global environmental protection. Today, oil is used as materials of many products, and energy is necessary for manufacturing and burning such materials, and carbon dioxide is generated. Efforts for reducing such energy and carbon dioxide are very important as global warming countermeasures.
For new efforts for reducing carbon dioxide as global warming countermeasures, much attention has been focused on the use of a plant-derived resource called biomass. Because the carbon dioxide generated in burning the biomass originates from the carbon dioxide which was present in the atmosphere and was taken in a plant through photosynthesis, the whole balance of input and output amounts of the carbon dioxide in the atmosphere is zero. In this manner, the property which does not affect an increase and a decrease in the carbon dioxide in the atmosphere is called carbon-neutral, and the use of the biomass having the carbon-neutral property is not considered to increase the amount of the carbon dioxide in the atmosphere. The biomass material made from such biomass is called by terms, such as a biomass polymer, a biomass plastic, or an oil-free polymer material, and the material of such biomass material is a monomer called a biomass monomer.
Also in the electrophotographic field there have been made many efforts to use the biomass which is a resource excellent in environmental safety and effective for suppressing an increase in the carbon dioxide.
For example, Japanese Unexamined Patent Publication JP-A 2008-122509 discloses a resin composition for an electrophotographic toner capable of obtaining an electrophotographic toner which contains a polyester resin having a softening temperature of 80 to 120° C. which is obtained from rosin as an essential component, and a polyester resin having a softening temperature of 160° C. or higher which obtained from a polyepoxy compound as an essential component, and has low-temperature fixability, a hot-offset resistance and development durability.
However, in the toner that is disclosed in Japanese Unexamined Patent Publication JP-A 2008-122509, when a rosin content in the resin composition for an electrophotographic toner is further increased in order to enhance utilization rate of biomass, preservation stability of the toner is deteriorated. There is a problem that in such a toner, at a developing step, toner particles are aggregated to each other at the time of agitating of the toner, and a charge amount is not stabilized.